The field of the invention is protective devices and the invention relates more particularly to shields and other covers for preventing water and other debris from fouling a device.
One type of remotely controlled valve operates by evacuating a measured volume of air through an air control line from a valve and then metering the air back into the line through a needle valve. The time required to meter in the entire evacuated volume of air is related to the time which the control device is preset. Although such devices work for long periods of time unattended in a clean environment, they are, unfortunately, easily caused to malfunction if the needle valve inlet is obstructed by water, dust or other foreign objects. The typical approach of providing a filter around the exterior of the valve has proved unsuccessful for preventing the intake of water falling from water leaks or condensation since the filter, over a relatively short period of time, can become soaked with water and clogged with debris. Furthermore, the cost of such filters is higher than desired.